Cables, ropes, chains, cords or other type of flexible line, herein referred to generally as a “cable,” may be wound onto or off of a drum by action of a motor and drive assembly that rotates the drum in connection with hoisting, winching and/or other cable reeling applications. During winding, the cable may become mis-wrapped on the drum or otherwise fouled, thereby causing operational delays or equipment damage. For example, a cable may be mis-wrapped so as to be out of alignment during the winding operation due to an excessive amount of slack in a standing portion of the cable, as a result of the cable becoming loose on the drum, and/or as a result of a failure of a level winding mechanism on the hoist. Further, a cable may be otherwise fouled due to splitting, kinks in the cable, or as a result of a broken strand of wire that may cause successive layers of wound cable to become mis-aligned.
Known cable foul sensors for cable hoists or winches use a flapper plate extending along the length of the drum. The flapper plate includes a sensing finger which extends into an opening of a cover disposed at an exterior of the drum and housing the area in which the cable is wound about the drum. A cable guide is used to guide the cable evenly onto or off of the drum. In instances where there is fouling of the cable at the drum, linear motion of the cable guide is impeded, causing the cable to wind upon itself and build-up to a height sufficient to trip the sensing finger of the flapper plate. The tripping causes an actuator to interrupt power to a motor and thereby stop the winding operation of the drum. (See, for example, U.S. Pat. No. 5,988,596 to Mitchell, et al., which is incorporated herein by reference.)
It is noteworthy that with known cable foul sensors, the winding operation is not immediately stopped upon an instance of cable fouling. Instead, the winding operation is interrupted after the mis-wrapped or otherwise fouled cable has built-up to a particular height sufficient to trip the sensing element. However, a relatively long delay between the occurrence of a cable foul and a remedial action taken in response to the foul makes it more difficult to reverse or correct any mis-alignment of the wound cable.
Accordingly, it would be desirable to provide a cable foul sensor that allows for relatively fast and efficient detecting of a cable mis-wrap or other cable foul during a winding operation.